Generally, an apparatus for measuring a three dimensional shape of a measurement object functions by radiating a grid-patterned light to the measurement object, receiving a grid image reflected from the measurement object and analyzing the grid image.
A conventional apparatus for measuring a three dimensional shape has one projecting unit for radiating a grid-patterned light to a measurement object and one imaging unit for capturing a grid image reflected from the measurement object. When a grid-patterned light is radiated at only one side in order to measure a three dimensional shape of a measurement object, a shadow region, at which a grid image does not arrive due to protrusion of the measurement object, is formed at an opposing side, thereby making it difficult to obtain a perfect three dimensional shape of the measurement object. In order to improve this, a three dimensional shape of a measurement object can be measured by a grid-patterned light radiated again after rotating and moving the projecting unit to the opposing side. A problem, however, exists in that such movement of the object impairs the efficiency of the measured procedure.
In addition, when capturing a grid image by using only one imaging unit, there has been a problem that a picture of a regular reflection surface cannot be accurately acquired due to regular reflection of the measurement object. In order to improve this, a method, in which regular reflectivity is reduced by using a filter or a control of light amount to acquire a picture of a regular reflect surface is sometimes used. With this procedure, however, there occurs a problem of reduction of measurement precision because a grid pattern of a three dimensional surface having a great regular reflectivity appears well but a grid pattern of an peripheral area does not appear well.